Skip to main content
Wellcome Collection homepage
  • Visit us
  • What’s on
  • Stories
  • Collections
  • Get involved
  • About us
Sign in to your library account
Search for anything
Library account
Take me back to the item page

Genetics / D.J. Cove.

  • Cove, D. J.
Date:
1971
Catalogue details

Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Genetics / D.J. Cove. Source: Wellcome Collection.

  • Front Cover
  • Title Page
  • Table of Contents
  • Back Cover
    23/228 (page 15)
    Previous page
    Next page
    diploid organisms 15 The hypothesis which Mendel put forward to explain the results from his single character crosses, which have been summarised in figure 7, can be tested. If the scheme is correct, then the cross between the purple-flowered Fi hybrid ^^heterozygous and the true-breeding white-flowered parental strain ^homozygous should give equal numbers of — (purple-flowered) and — (white-flowered) progeny (see parents ±_ w JUL w by reduction division gametes + w w zygotes (in equal numbers upon random fusion) adult plants _+ w w w purple-flowered white-flowered Figure 8. (For explanation, see above.) figure 8 for breeding scheme). Mendel found that this was so. He obtained 84 purple-flowered and 81 white-flowered progeny, which is in close agreement to the predicted 1 : 1 ratio. This type of cross, where an Fi hybrid is crossed to one of the parent strains is called a back cross. The special case where the Fj hybrid is crossed to a strain homozygous for the recessive alleles involved (this need not necessarily be a parent strain) is called a test cross. The theory of dominance which proposes that the heterozygous strain resembles one of the two homozygous strains which gave rise to it, may at first sight seem to be proposing a rather unlikely situation. However it will be recalled that mutation commonly leads to the absence of an enzyme. It is probable that the w allele has arisen from the + allele by mutation, and that strains homozygous for the w allele are unable to make an enzyme necessary for the synthesis of
    page 11
    19
    page 12
    20
    page 13
    21
    page 14
    22
    page 15
    23
    page 16
    24
    Previous page
    Next page

    Wellcome Collection

    183 Euston Road
    London NW1 2BE

    +44 (0)20 7611 2222
    info@wellcomecollection.org

    • Getting here

    Today’s opening times

    • Galleries
      10:00 – 20:00
    • Library
      10:00 – 20:00
    • Café
      10:00 – 20:00
    • Shop
      10:00 – 20:00

    Opening times

    Our building has:

    • Step free access
    • Hearing loops

    Access information

    • Visit us
    • What’s on
    • Stories
    • Collections
    • Get involved
    • About us
    • Contact us
    • Jobs
    • Media office
    • Developers
    • Privacy and terms
    • Cookie policy
    • Manage cookies
    • Modern slavery statement
    TikTok
    Facebook
    Instagram
    YouTube

    Except where otherwise noted, content on this site is licensed under a Creative Commons Attribution 4.0 International Licence